-LRB- CNN -RRB- -- A very wise district attorney once gave a piece of pragmatic advice to a young assistant prosecutor investigating a prominent political figure . The case involved evidence that could possibly support a criminal indictment yet was unlikely to result in a conviction . That DA 's advice to his young assistant : `` If you are going to shoot at the king , you 'd better be able to kill the king . ''

The wisdom of that literary caveat , self-evident to those who pursue the powerful , is particularly relevant to the Gov. Chris Christie scandal involving traffic delays at the George Washington Bridge .

In the days and weeks to come , prosecutors with potential jurisdiction over a criminal investigation of Christie and his political acolytes regarding the agonizing traffic tie-up -- and a possible subsequent cover-up -- will be carefully screening the evidence . They would be wise to consider the pragmatic advice about king-slaying , which has been quietly observed by sensible prosecutors for years .

Three prosecutors have potential jurisdiction : Manhattan District Attorney Cyrus Vance Jr. ; Bergen County , New Jersey , Prosecutor John Molinelli ; and U. S. Attorney Paul Fishman , the man who replaced Christie as New Jersey 's federal prosecutor .

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Vance is a Democrat , known for nonpartisanship . Molinelli was appointed Bergen County prosecutor by Christie 's predecessor , a Democrat . And Fishman is the appointee of a Democratic president with the blessing of New Jersey 's two U.S. senators , both Democrats .

All three prosecutors enjoy reputations for fairness and integrity in the conduct of their offices , but it would be a deft trick for each of the three to reassure residents of New York , New Jersey and the nation that any investigation -LRB- and possible prosecutions -RRB- will be free of political influence .

Though Vance may have a shred of a right to prosecute -LRB- because the bridge touches land in New York County -RRB- , I suspect he is wise enough to know that his Manhattan DA 's Office has no business interfering in this Jersey mess .

Molinelli , though , has more legitimate concerns -- the individuals most affected were those living in the Bergen County towns he serves . There is even a New Jersey criminal statute entitled `` Official Misconduct '' relating to the abuse of governmental authority by public servants for personal gain that may be relevant to the bridge brouhaha .

As a lame duck prosecutor appointed by Christie 's predecessor , Democrat John Corzine , Molinelli will face heavy scrutiny if he tries to slay the king -- in this case , the governor .

Enter Fishman , the U.S. attorney and potential white knight . Though a registered Democrat appointed by President Barack Obama , he was sworn into office by Justice Samuel Alito , a conservative icon .

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Fishman has sterling credentials and a reputation for fairness . He 's vowed since 2009 to keep politics out of his powerful office and to depoliticize it after many prosecutions by his predecessor were criticized as having been political in nature . That predecessor ? Chris Christie .

The legal bloodlines of this case are more mixed than the contents of a Meadowlands landfill . Fishman , as the ranking Fed , can force local Jersey prosecutors out of the ring through a variety of tactics , if he chooses to do so . Bergen 's Molinelli could insist on proceeding -- but , in the face of a potentially more serious federal intervention , most local prosecutors would back off .

Why would the locals defer to Fishman ? The answer is entirely pragmatic . These prosecutors have to work together on many overlapping cases as they each seek to round up New Jersey 's notorious collection of bad guys . And a local DA generally defers to a federal prosecutor who can supersede him in a variety of ways . Politics and pragmatism enters every field in our system , even criminal prosecutions .

Given Christie 's political prominence -- both in New Jersey and nationwide -- you are certain to see , in coming days and weeks , a steady stream of information discreetly leaked to news media regarding ongoing criminal and civil investigations .

Though Christie will endure potentially embarrassing legislative hearings , predictable federal subpoenas , and possible damage to his promising presidential candidacy , I think it 's safe to say the governor will not be indicted . There is a greater downside to that scenario : Voters may be convinced it is indeed a political witch hunt intended to cripple a leading presidential candidate .

Despite some titillating hints from insiders , the bulk of evidence relating to the bridge fiasco probably remains undisclosed .

Christie , as a former prosecutor , is far too smart to have left his fingerprints or interoffice `` DNA '' on any specifics of the bridge fiasco .

Even if a former aide or political pal testifies against the governor as part of a prosecutorial deal , most jurors would want to see corroboration . Nobody likes a snitch , even a political one . The case will look like a political hatchet job and the wounded , angry `` king '' may strike back with political vengeance . The public will doubt the integrity of the prosecutor destroying his reputation .

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More of his political aides may fall as the search for scapegoats continues , but the governor will not be taken away in handcuffs . Why ? Because as that wise prosecutor once said , `` If you are going to shoot at the king , you 'd better be able to kill the king . ''

The opinions expressed in this commentary are solely those of Paul Callan

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Paul Callan : Prosecutors are loath to charge a powerful political figure

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He says it 's unlikely that Chris Christie left his fingerprints on the bridge issue

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The rule is that if you charge a powerful figure , you 'd better be able to win the case , he says

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Callan : Prosecutors will be wary of perception that they are on a political witch hunt